feat: add multi-platform packaging and auto-update infrastructure

- Add PyInstaller configuration (clide.spec) for cross-platform builds
- Add build scripts for macOS (DMG), Linux (AppImage), and Windows (Inno Setup)
- Add Gitea Actions CI/CD workflow for automated releases
- Add auto-update service with Gitea API integration
- Add 'clide update' CLI command for checking and installing updates

Packaging outputs:
- macOS: Signed/notarized .app bundle in DMG
- Linux: Portable AppImage (glibc 2.17+)
- Windows: Inno Setup installer

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/build-linux.sh

@@ -0,0 +1,85 @@
+#!/bin/bash
+# Build script for Linux AppImage distribution
+# Creates a portable AppImage that runs on most Linux distributions
+#
+# Prerequisites:
+#   - wget (for downloading appimagetool)
+#   - FUSE (for running appimagetool)
+#
+# Usage: ./scripts/build-linux.sh [VERSION]
+
+set -e
+
+VERSION="${1:-1.0.0}"
+ARCH=$(uname -m)
+
+echo "========================================"
+echo "Building Clide $VERSION for Linux ($ARCH)"
+echo "========================================"
+
+# Ensure we're in the project root
+cd "$(dirname "$0")/.."
+
+# Build with PyInstaller
+echo "Building with PyInstaller..."
+pyinstaller clide.spec --clean --noconfirm
+
+# Create AppDir structure
+echo "Creating AppDir structure..."
+rm -rf dist/Clide.AppDir
+mkdir -p dist/Clide.AppDir/usr/bin
+mkdir -p dist/Clide.AppDir/usr/share/applications
+mkdir -p dist/Clide.AppDir/usr/share/icons/hicolor/256x256/apps
+
+# Copy binary
+cp dist/clide dist/Clide.AppDir/usr/bin/
+
+# Copy desktop file
+cp packaging/clide.desktop dist/Clide.AppDir/
+cp packaging/clide.desktop dist/Clide.AppDir/usr/share/applications/
+
+# Create placeholder icon (TODO: Replace with actual icon)
+# For now, create a simple placeholder
+if [ ! -f packaging/clide.png ]; then
+    echo "Note: No icon found at packaging/clide.png, AppImage will have no icon"
+else
+    cp packaging/clide.png dist/Clide.AppDir/clide.png
+    cp packaging/clide.png dist/Clide.AppDir/usr/share/icons/hicolor/256x256/apps/clide.png
+fi
+
+# Create AppRun launcher
+cat > dist/Clide.AppDir/AppRun << 'EOF'
+#!/bin/bash
+# AppRun - Entry point for AppImage
+SELF=$(readlink -f "$0")
+HERE=${SELF%/*}
+export PATH="${HERE}/usr/bin:${PATH}"
+export TERM="${TERM:-xterm-256color}"
+exec "${HERE}/usr/bin/clide" "$@"
+EOF
+chmod +x dist/Clide.AppDir/AppRun
+
+# Download appimagetool if needed
+APPIMAGETOOL="appimagetool-${ARCH}.AppImage"
+if [ ! -f "$APPIMAGETOOL" ]; then
+    echo "Downloading appimagetool..."
+    wget -q "https://github.com/AppImage/AppImageKit/releases/download/continuous/appimagetool-${ARCH}.AppImage" \
+        -O "$APPIMAGETOOL"
+    chmod +x "$APPIMAGETOOL"
+fi
+
+# Create AppImage
+echo "Creating AppImage..."
+rm -f "dist/Clide-$VERSION-linux-$ARCH.AppImage"
+ARCH=$ARCH ./"$APPIMAGETOOL" dist/Clide.AppDir "dist/Clide-$VERSION-linux-$ARCH.AppImage"
+
+# Clean up AppDir
+rm -rf dist/Clide.AppDir
+
+echo ""
+echo "========================================"
+echo "Build complete!"
+echo "Output: dist/Clide-$VERSION-linux-$ARCH.AppImage"
+echo ""
+echo "To run: chmod +x dist/Clide-$VERSION-linux-$ARCH.AppImage && ./dist/Clide-$VERSION-linux-$ARCH.AppImage"
+echo "========================================"